Month: December 2016

Byzantine Structure of the Cosmos

A diagram showing the nature of the cosmos from earth at the center to God at the top, passing through the various levels‚—e.g., the elements, ether, angles—from a 16th-century copy of Nicephorus Blemmydes’ “Epitome physica” Oxford, Bodleain Barocci 94, fol. 27v.

This diagram showing the structure of the cosmos comes from Nicephorus Blemmydes’ “Epitome physica.” At the center is the sphere of elemental earth surrounded by a narrow sphere of water. Then a broad sphere of air surrounds them capped by the sphere of fire. Separating the elements from the heaves is the sphere of the moon. Beyond that is the ether, the “ΑΙΘΗΡ,” where we see planets and stars. Beyond this is the “Water beyond the heavens” surrounded by the “Place of the angels.” A hierarchy of nine levels of angels, archangels, and beyond culminates in the Trinity at the top.

Born just before the Latins sacked Constantinople in 1204, Blemmydes fled the capital and studied mathematics, medicine, astronomy, logic, as well as theology and rhetoric in Asia Minor, especially Nicaea. He participated in the controversies between the Eastern and Western Churches, agreeing with the Western Church’s beliefs on such issues as the procession of the Holy Ghost from the Father through the Son. He was also renowned for establishing a school, where the young George Akropolites studied. Like so many Byzantine polymaths, he ultimately retired from public life to a monastery he had built.

A Spherical Astrolabe

The only spherical astrolabe that survives is this one made in A.H. 885 (1480 CE), most likely somewhere in present-day Syria. Today it is in the Museum of the History of Science, item # 49687.

The most common type of astrolabe is the planispheric astrolabe, which works by projecting the sphere of the heavens onto a plane in a way that preserves angular distances and allows the user to carry out a wide variety of calculations.[1] The rarest form type of astrolabe is the spherical astrolabe. Although Latin and Arabic descriptions of such instruments exist, and other sources indicate that some mathematicians might have owned spherical astrolabes, only this single example survives. This astrolabe is about the size of a baseball, .[2]

The rete on this astrolabe is a cage-like structure that would rotate around the globe inside it.[3] As with the rete on a planispheric astrolabe, this one includes a number of bright stars, 20 to be precise, a zodiac, and a meridian line. Unlike a planispheric astrolabe, which has different plates engraved for each latitude to depict the portion of the sky above the horizon at that latitude, this spherical astrolabe as a single “plate”—the globe on which the heavens are depicted. To adjust it for each latitude there were a different holes in the globe. A pin was inserted through a hole the cage-like rete and into the hole in the globe, both fixing the portion of the sky visible from the latitude and providing a point around which the heavens would rotate.

The maker signed and dated the globe, “The work of Mūsa. Year 885.” Unfortunately, we know nothing more about the maker, whose name is rather common. Based on the decoration and calligraphic style (a Kufic script, if you care), it seems likely to have been produced in the Eastern Mediterranean somewhere, probably Damascus or Cairo.

If you want to see more, it is Museum of the History of Science, item #49687.


  1. The mariner’s astrolabe is not, as far as I care, an astrolabe. The mariner’s astrolabe is an instrument for observing the altitude of a celestial object, e.g., the sun, and from that determining latitude. For me, the key difference is the fact that mariner’s astrolabes cannot be used to carry out any of the various calculations that define the planispheric astrolabes. I realize that some people want to call the mariner’s astrolabe a type of astrolabe. So be it. I, however, will not.  ↩

  2. For those more familiar with cricket, a cricket ball and baseball are nearly the same size: men’s cricket ball is 224–229mm in circumference; an official, professional baseball is 228–234mm in circumference. Field hockey your sport? A field hockey ball is about the same circumference, 224–235mm. Don’t like sports? Neither do I really.  ↩

  3. The rete is the map of bright stars that rotated about the pole. For more information about astrolabes, see my Guide to the Astrolabe.  ↩

A Byzantine form of Geomancy?

A figure that correlates the planets, signs of the zodiac, and figures, which seems to be related to some geomancy of some form. “Cleromancy,” Harley MS 5596, fol. 4v.

This illustration from a 15th-century manuscript seems to be a type of geomantic figure that correlates the planets, signs, and figures (arrangements of dots). It shows the standard astrological relationships between planets and signs. Starting at the top and proceeding counterclockwise from the moon:

  • Moon — Cancer
  • Mercury — Gemini and Virgo
  • Venus — Taurus and Libra
  • Sun — Leo
  • Mars — Aries and Scorpio
  • Jupiter — Sagittarius and Pisces
  • Saturn — Capricorn and Acquarius

We also see a figure of dots associated with each planet/sign combination.

The planets and signs are each associated with a pattern of dots, as they are in geomancy. Here the planets and signs have been labeled.

In its most generic sense, geomancy involved interpreting random markings of dots. Four rows of dots were grouped into figures, each named, associated with a planet, a sign, day or night, and other properties. There were sixteen such figures. This diagram was, perhaps, a form of geomancy or a related mantic practice (the generic title given to this work, “cleromancy”—divination by drawing lots, seems more closely related to the first figure than to this one.)

Various forms of divination were widely practiced (or at least discussed) throughout the Byzantine world, ranging from the recognizable astrology and necromancy to the relatively obscure (at least today) catoptromancy and lecanomancy—divination through interpreting images in mirrors or patterns in liquids in bowls. Both practices could both be part of long and complicated rituals that compelled demons to appear on the surface of the liquid or in the mirror. The demons could be commanded to reveal the future.

16th-century Surgical Instruments: Forcipes denticulatae

Some of the ornate forceps in Jean Tagault’s De chirurgica institutione (Venice, 1544). I particularly like the little dragon heads on the ends of the handles. This copy is from Haverford’s Special Collections, call #R128.6 .T3 1544.

Jean Tagault was a lecturer in surgery and anatomy at the University of Paris in the mid–16th century. His manual on surgery included not only descriptions of how to perform various procedures that ranged from the relatively trivial and non-invasive to the more cringe-worthy invasive operation. Here he displays a particularly ornate pair of toothed forceps with dragon heads at the end of the handles. As with the forceps on the preceding page, these could be used to remove spines, barbs, thorns, stingers, and other pointed objects.

As with many surgery manuals, this one also includes discussion of anatomy.[1] Here we see a standard illustration of the human skeleton, with the many bones and cartilage labeled.

Jean Tagault’s illustration of the human skeleton in his De chirurgica institutione (Venice, 1544), from Haverford’s Special Collections, call #R128.6 .T3 1544.

Jean Tagault’s De chirurgica institutione was a widely read surgery manual.[2] First printed in 1543 in Paris, it was reprinted five times before the end of the decade and continued to be printed in Latin until the end of the century. In the first few years it was translated into French and German, by 1559 had been translated into Dutch, and by 1585 had been translated into Italian. Portions were excerpted and translated into English. Another Italian edition appeared as late as the early 17th century.


  1. Allen Shotwell has a nice discussion of the ways that instruments and anatomical illustrations often appeared in the same texts, “Showing the Instruments.”  ↩

  2. Clearly, I’m inferring readership from the books printing history. It is possible that nobody actually read the book, though in that scenario the explanation for its many printings and translations becomes a bit perverse. So let’s all agree that there is some correlation between number of printings & translations and readership.  ↩

The Mouse Ear Plant

The Mouse-ear and Isatis plants from a 9th-century illustrated copy of Dioscorides’ “De materia medica,” BN graec. 2179, fol. 5r

These illustrations are found in a 9th-century manuscript of Dioscorides’ “Περὶ ὕλης ἰατρικῆς,” known more commonly by its Latin title, “De materia medica.” The top plant is called Μυοσωτίς (mouse-ear plant); the bottom is Ἰσάτις (sometimes identified as “woad”). Note the reclining figure under the Μυοσωτίς. Note also the Greek and especially the Arabic and Latin glosses added to the text. Next to both plants are their names in Arabic and Latin. There is additional Arabic added vertically in the left margin and at the very top right corner, and some Latin under the Ἰσάτις. Latin numerals seem to number these plants 48 and 49.[1] Such Arabic and Latin glosses continue throughout this copy and testify to the work’s circulation in different linguistic contexts and the effort earlier scholars put in to make the work comprehensible.

Today Dioscordes’ “Περὶ ὕλης ἰατρικῆς” is one of the most widely known works from the Byzantine period, thanks in part to its beautiful illustrations of plants.[2] Written sometime in the mid-first century CE, the “De materia medica” compiles medical uses for hundreds of plants from across the Mediterranean—Dioscorides was a surgeon in Nero’s army and travelled widely around the Mediterranean. In addition to its illustrations, the work included descriptions of each plant’s virtues and therapeutic effects.


  1. It is unclear what these numbers suggest—these plants are 8th and 9th plants in the this copy, so perhaps the first folia have been lost. No doubt one of the scholars who has studied this copy explains what these numbers mean.  ↩

  2. Individual copies of the work are themselves well known for different reasons, e.g., “Vienna Dioscorides” is the oldest surviving copy, prepared for the emperor’s daughter, Juliana Anicia; the “Dioscurides Neapolitanus” is a nice copy and the version used for the World Digital Library.  ↩